What the heck are you guys talking about?!
This issue is coming up again; the issue was previously resolved with 10.0.3.
Followed all steps in KB, followed tips found on reputable FCPX sites, no luck.
We are opening a ticket with Apple, hopefully they'll give us a fix, or they'll acknowledge the regression and will issue a patch ASAP.
The issue persists even after 10.0.6 update is applied.
Mac Pro exceeds HW/SW requirements.
Rebuilt manually, updated manually, FCPX 10.0.6 reinstalled, launches fine a few times.
Eventually the same "Restoring the window layout" error comes up rendering FCPX unusable.
The issue is widespread on these forums.
Apple's KB TS4169 steps do not resolve the problem.
I don't speak spanish...but I digress...